Related articles

In a chilling warning, he added: “We don't have any defence that could deny the employment of such a weapon against us.”

The Air Force Commander has previously branded Russia one of the “most significant threats” to the US and said that America must quickly update its defences.

However, he stressed that if he had an order from President Donald Trump or any of his successors to launch nuclear weapons, it can be refused if that order is determined to be illegal.

General Hyten told a panel at the Halifax International Security Forum that he and Mr Trump have had conversations about such a scenario and that he would tell Mr Trump he could not carry out an illegal strike.

Putin’s war chest: Warships, armies, missiles and guns REVEALED

Tensions between the UK and Russia are at breaking point. If things were to escalate to war, Vladimir Putin owns a terrifying war chest at his disposal.

Mr Trump’s taunting tweets aimed at Pyongyang have sparked concerns primarily among congressional Democrats that he may be inciting a war with North Korea.

During testimony before the Foreign Relations Committee earlier this month, retired General Robert Kehler, who served as the head of Strategic Command from January 2011 to November 2013, also said the US armed forces are obligated to follow legal orders, not illegal ones.

General Hyten said he has talked it over with Mr Trump.

He said: “I think some people think we’re stupid. We’re not stupid people. We think about these things a lot. When you have this responsibility, how do you not think about it?”